Tire repair operations, such as tire retreading operations, are generally used to extend the useful service life of a tire. Typical tire retreading operations include removing previously worn tread from a tire and bonding new tread in its place. Tires may be retread or repaired one or more times as a less expensive alternative to purchasing new tires, providing particular advantages for large-scale operations such as trucking, bussing and commercial aviation.
Generally, some level of non-destructive testing (NDT) of the tire prior to repair is conducted to determine whether it is appropriate to perform the repair operation. Visual inspection methods can be used to validate the integrity and, subsequently, the viability of retread and/or repair of tire casings for retread. For instance, the inside and outside surface of a tire can be visually inspected by an operator using special lighting to inspect for defects such as crazing, cracks, snags, bulges, depressions, gouges, abrasions, marbling, bubbles, blisters, separations, and other defects. Visual inspection methods, however, are subjective, inconsistent, and can require extensive training. Moreover, due to high operator turnover, difficulty exists in retaining expertise.
High Voltage Discharge (HVD) testing can be performed in place of or supplemental to visual inspection. HVD testing can be used to identify anomalies in the inner liner of a tire that penetrate the insulating material of the inner liner. HVD testing, however, will not identify surface anomalies that are not deep enough to sufficiently reduce the dielectric level of the tire so that an electric discharge can occur.
Other NDT techniques include monitoring temperature distribution on the surface of a tire to inspect the tire for delamination. Such techniques, however, can require the application of significant heating or cooling to the surface of the tire, which is not suitable for detecting minor surface anomalies such as pin-holes, abrasions, cracks, or other minor defects on the surface of the tire. Moreover, such techniques can require subjective visual inspection of thermal images of the tire and do not provide for objective identification, location, and classification of surface anomalies.
Thus, a solution is needed for detecting tire surface anomalies during an automated inspection of a tire. The solution can replace the necessity of subjective visual inspection of the tire by providing an objective analysis of surface anomalies that can supplement or replace HVD testing. A solution that can detect minor surface anomalies, such as pin-holes, small cracks, abrasions, and other defects in a tire surface would be particularly useful.